Green’s early work on x-rays involved his access to vacuum tubes, which were in use in the lamps he was manufacturing, either through Green Electric Lamp Company, the Aetna Electric Company, or both. John Bauer was a glassblower at Aetna Electric Company, and Bauer became Green’s partner in Green & Bauer, which was in operation as early as November 1896.
It seems likely that there is at least one patent application, for the device sold to Hartford Hospital, that would have been filed before November 1896.